21,872
21,872 is a composite number, even.
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 20
- Digit product
- 224
- Digital root
- 2
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 27,812
- Recamán's sequence
- a(168,019) = 21,872
- Square (n²)
- 478,384,384
- Cube (n³)
- 10,463,223,246,848
- Divisor count
- 10
- σ(n) — sum of divisors
- 42,408
- φ(n) — Euler's totient
- 10,928
- Sum of prime factors
- 1,375
Primality
Prime factorization: 2 4 × 1367
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- twenty-one thousand eight hundred seventy-two
- Ordinal
- 21872nd
- Binary
- 101010101110000
- Octal
- 52560
- Hexadecimal
- 0x5570
- Base64
- VXA=
- One's complement
- 43,663 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒁹𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺
- Greek (Milesian)
- ͵καωοβʹ
- Mayan (base 20)
- 𝋢·𝋮·𝋭·𝋬
- Chinese
- 二萬一千八百七十二
- Chinese (financial)
- 貳萬壹仟捌佰柒拾貳
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,872 = 1
- e — Euler's number (e)
- Digit 21,872 = 4
- φ — Golden ratio (φ)
- Digit 21,872 = 9
- √2 — Pythagoras's (√2)
- Digit 21,872 = 3
- ln 2 — Natural log of 2
- Digit 21,872 = 9
- γ — Euler-Mascheroni (γ)
- Digit 21,872 = 0
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21872, here are decompositions:
- 13 + 21859 = 21872
- 31 + 21841 = 21872
- 73 + 21799 = 21872
- 199 + 21673 = 21872
- 211 + 21661 = 21872
- 223 + 21649 = 21872
- 271 + 21601 = 21872
- 283 + 21589 = 21872
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 95 B0 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.85.112.
- Address
- 0.0.85.112
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.85.112
Unspecified address (0.0.0.0/8) — "this network" placeholder.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.
The digit sequence 21872 first appears in π at position 18,811 of the decimal expansion (the 18,811ordinal-suffix:th digit after the integer 3).
Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.